Flammable vapor protection



Dec. 12, 1950 w. J. WILLENBORG FLAMMABLE VAPOR PROTECTION 2 Sheets-Sheet 1 Filed June 22, 1946 INVENTOR. W O mf A M Dec. 12, 1950 w, J, WILLENBQRG 2,533,339

FLAMMABLE VAPOR PROTECTION Filed June 22, 1946 2 Sheets-Sheet 2 IN V EN TOR.

Patented Dec. 12, 1950 FLAMMABLE VAPOR PROTECTION Walter J. Willenborg, Weehawken, N.

to Jabez Burns & Sons, Inc., a corporation of New York 1., assignor New York, N. 1..

Application June 22, 1946, Serial No. 678,556 3 Claims. (Cl. 177-311) This invention relates to improved means for detecting the presence of flammable vapors and gases in locations where their presence may become dangerous; and to the automatic control of devices for giving a warning signal of the approach towards a dangerous condition. It also relates to the automatic control of means for preventing the occurrence of a dangerous condition and for preventing explosions which might otherwise occur.

The method disclosed herein is covered in my pending divisional application Serial No. 14,322, filed March 11', 1948, now abandoned.

In my U. S. Patent No, 2,255,551, granted September 9, 1941, and in my co-pendingapplication Serial No. 646,511, filed February 9, 1946, the detection of the presence of certain gases or vapors is based upon the thermal conductivity of the gases to be detected. An increase in the presence of such gases or vapors by their higher thermal conductivity lower the temperature of the resistive conductor or conductors exposed thereto and thereby gives an indication of their presence. Such a method of detection is applicable to certain vapors and gases but not to certain others and is not sufliciently sensitive in detecting some vapors and gases. By the present improvement the method of detection is based upon a different process and instead of depending upon the change in thermal conductivity of the vapors or gases to be detected, depends upon the catalytic action of the vapors or gases with reference to the detectin element or elements. This catalytic action increase the temperature of the detector, or resistive conductor, and thereby increases its resistance for obtaining a responsive indication, as distinguished from lowering the temperature and resistance in the prior thermal conductivity method. The catalytic action is obtained by maintaining the temperature of the detecting element or elements suiiiciently high so that the presence of the vapors or gases to be detected will cause the action to occur and in increasing degree as the presence of such gases increases. One object of the present improvement is therefore to provide improved means for detection particularly applicable to certain vapors and gases such as gasoline and alcohol vapors, ethylene, hydrogen and the like. Another object is to provide improved means of detection which is highly sensitive in response in detecting their presence in minute amounts and in giving pronounced indications when the presence of such vapors or gases increases.

Another object i to cause the actuation of an alarm or signal when the presence of such vapors perature to the glow point, thereby eliminating a source of ignition. These and other objects and advantages will be understood from the following description and accompanying drawings which illustrate preferred embodiments of the invention.

Fig. 1 is a diagram showing the detecting, responsive and controllin apparatus; Fig. 2 is a diagram showing another application of the invention; and Fig. 3 is a diagram showin a modification of a portion of the control.

Referring to Fig. 1, the detecting cell or analyzer of the vapors or gases to be detected is shown formed of a metal block i having an opening 2 passing through it. A recess 3 is formed in the block which communicates with the passage 2 at one end of the recess and is sealed at its outer end by a disk 4 of insulating material through which pass leads which support the resistive conductor 5 within the recess. A metal screen 3b of a line mesh is shown covering the inner end of the recess. The block also has a recess 3a which is closed against the passage 2 and is sealed at its outer end by an insulating disk 4a. A pair of leads pass through this disk and support a resistive conductor 5a within the closed recess 3a. The cell unit or block is positioned at any location where the presence of vapors or gases is to be detected and is shown located within an enclosure 6. This may be a more or less open or enclosed space such as the bilge of a ship or motor boat, a room or buildin where operations are carried on which might result in the accumulation of flammable vapors or gases. The drawing indicates a passage open at both ends and within which some chemical process might be conducted which gives off flammable vapors. A motor driven fan or blower 1 is shown at one end of the passage for blowing air through the passage for clearing out or reducing the amount of flammable vapors or gases when they accumulate towards a dangerous condition.

The resistive conductor 5 is in the form of a fine bare wire or filament which may be zig-zag, coiled or straight in some cases and is of a mav 3 terial which has a catalytic action when sufiiciently heated in the presence of gasoline and alcohol vapors, ethylene, hydrogen and the like in any air mixture containing even slight amounts of such flammable gases or vapors. In order to obtain this catalytic action for detection purposes the temperature of the filament or resistive conductor 5 must be maintained by auxiliary means at a temperature of at least 85 C.; and the action increases with increasing temperatures of the conductor. But the temperature should be kept below that at which the filament glows as otherwise an explosion might result; and for that reason, as a special safety precaution, the open end of the recess 3 may be covered by the wire screen 3b to reduce the fire hazard in case the filament should ever become heated to a glowing temperature. However, there is a wide range of safe operating temperatures below'the glow temperature and above 85 C. For example, in the case of platinum the temperature at which it will begin to glow is about 425 C.; and a similar wide range exists for other adaptable metals. The catalytic action increases in the presence of flammable gases or.

vapors with any increase in their presence in any mixture with air or other oxygen containing gases. Likewise the catalytic action due to their presence heats the filament or resistive conductor and such increase in temperature further increases the action. It follows that a pronounced change of temperature of the catalyst filament may'occur under comparatively small increase in the presence of flammable gases and thereby may be made to respond with a high degree of sensitivity. The size and length of the resistor or filament and the temperature at which it will be maintained for detection will depend upon the material of the filament, the vapors or gases to be .detected and the limit in the percentage presence of the vapors or gases within which they are to be restricted before an alarm or responsive control is to take place.

The material of the filament or resistor may be any catalyst active as such in the presence of the flammable gases or vapors or mixtures thereof when air or oxygen is present. As an example may be mentioned platinum, palladium, rhodium, various alloys thereof and other compositions of metals to which promoters have been added for securing or increasing their catalytic action. Such catalysts vary in their efiective action in the presence of various flammable vapors or gases and selections may be made accordingly and depending on the degree of response required in a particular case. These materials all have a positive temperature coefiicient of resistance and their heating by the catalytic action increases their resistance which increase i utilized in a bridge circuit for obtaining an indication of the presence of the flammable gases or vapors in an air atmosphere or other mixture and for securing desired controls at predetermined limits.

As to the filament or resistor 5a, this is sealed from any contact with the flammable vapors or gases and, of course, unafiected thereby and forms another part of the bridge circuit, as later explained. It may be different in size and material fromthe filament 5 but is preferably made the same for best results so as to serve in the bridge circuit to compensate for change in ambient temperature of the cell unit and balance any change in the temperature of the filament 5 due to ambient temperature changes.

iii)

The indicating and controlling apparatus shown in the drawing will now be described. A direct current source 8, shown as a battery, supplies current through a manually operated switch 8a to the lines 9 and 9a. A lead from the line 9 passes to a variable resistive device l0 and then to a milli-ammeter H from which a connection extends to a bridge circuit such as a Wheatstone bridge. One side of the bridge from the point [2 comprises the resistor l3, the variable balancing resistor 14 and the resistor [5 to the point it. The other side of the bridge from the point l2 comprises the resistor 5a, resistor 5 and then to the point It. A contacting type of galvanometer H is connected from the contact lea of the variable resistor it to the point lie in the connection between the resistors 5 and 5a. The galvanometer will therefore indicate from its zero central indicating position any unbalancing of the bridge circuit. The adjustable resistor i4 is provided for securing a zero reading of the instrument I! when no flammable vapors or gases are present in the cell unit or for any selected condition. The return connection from the point l6 of the bridge to the source is made by a lead wire Hi to a fixed contact l9 and then through a movable contact l9a to the supply line 911. An electromagnet, indicated for simplicity as a solenoid, has a controlling winding 20 for aiiecting the position of its movable contacts Mia and Zia. This winding is connected in series with a resistor 22 from supply line 9 to the fixed contact I9. A push button switch 23 is adapted to energize the magnet winding when temporarily closed by a circuit from line 9, resistor 22, winding 20, switch 23 and then to line 9a. The movable vane Ha of the galvanometer I7 is electrically connected to one terminal of the winding 20, the other terminal being connected to both of the fixed galvanometer contacts Ilb engaged at the limiting positions of the vane Ila. When either of the contacts l'lb is engaged by the vane, the winding 20 is deenergized.

When the winding 20 is not excited, its movable contact I9a engages a fixed contact 19b. From this contact extends a connection to a red signal light 24 connected in parallel with an alarm signal 25 to the line 9. A green signal light 26 is connected from the line 9 to the fixed contact IS. The operation of the fan or blower l is controlled by the movable contact vZia of the magnet. This contact is connected through a switch 2'! when closed to one side of a source 28, indicated as an alternating current source. The fixed contact 2! of the magnet is connected through the blower l to the switch 21 and through it to the other side of the source 28. The switches 27 and 8a may be operated manually in unison by a handle 29.

The drawing shows the parts in their inoperative condition. Operative conditions are secured by first closing the switches 8a and 2?. The switch So then supplies current to the danger signal 25 and alarm 25 through the contacts [9a and lilb. The switch 27 then supplies current to the blower l through the contacts 2i and 25a. This condition may be continued for a short time to permit the blower to clear the protected space of any flammable vapors or gases which may have accumulated during shutdown. The push button switch 23 is then closed momentarily which excites the winding 2a through the circuit already explained. The magnet then moves its contact 89a to disengage ausaaao the contact I 9b and engage the contact I I. This opens the circuit to the light 24 and alarm 25 and closes the circuit through the safety light 26. It also closes a holding circuit of the winding 20 from line 9 through resistor 22, winding 20, wire l8 and contacts l9 and I 9a to line la which maintains the winding energized after the push button switch is opened. The blower circuit is also opened at the contacts 2i and 2| 0. which stops the blower. In some cases the opening of these contacts may serve merely to reduce the speed of the blower if desired as by inserting a resistor in series in the blower circuit.

The energization of the magnet winding also closes the bridgecircuit by the closing of the contacts is and |9a b a circuit from line 8, adjustable resistor 10, ammeter ll, through the bridge circuit to connection l8, and contacts [9 and IQa to line So. The device i is then ad- Justed to cause suflicient current topass through the bridge circuit to bring the temperature of the filament or resistor 5 to at least 85 C. to insure that this filament will act catalytically in the presence of flammable vapors or gases. The value of the current supplied to the bridge for this purpose is predetermined which enables the operator to adjust the resistive device l0 until the reading of the milli-ammeter it gives the required current.

In case flammable vapors or gases together with air or oxygen are present within the enclosure 6 which may be remote from the indicating and control apparatus, the resistor 5 will act as a catalyst which in turn causes the heating of the resistor and increase in its resistance. This unbalances the bridge circuit because the resistor 5a is unaffected which results in the vane or pointer ila being moved say t the right a certain amount and thereby indicate the pres. ence of the flammable vapors or gases;-and any increase in the presence thereof will cause a corresponding further deflection of the pointer Ha to the right. The right-hand fixed contact i7?) is adjusted at a position .such that when the presence of such vapors dangerous condition, the vane i'ia. will engage the right-hand contact ilbl This, as already explained by the circuit connections will shortcircuit the winding 20 and deenergize it. The movable contacts Mia and 21a then move to the position shown in the drawing which opens the circuit to the safety light 26 and closes the circuit to the danger light 24 and alarm 25. It also closes the circuit to the blower l which then automatically serves to clear the danger space of the flammable gases or vapors, or to reduce their percentage presence to within a safe limit. In case no automatic means are provided for automatically reducing the danger, the operator will act to remedy the condition. After the approach to a dangerous condition is overcome, the operator will close the push button switch or gases approach a 23 to again place the apparatus in protective condition.

The automatic deenergization of the control winding 20 when a dangerous condition is appreached also serves to open the bridge circuit at the contacts i9 and lea which results in cuttin off the supply of heating current to the resistor or filament 5. This avoids the possibility of the element 5 being further heated which if continued might reach a glowing condition and cause an explosion or fire if the presence of the flammable vapors or gases were permitted to increase. As a further precaution the screen 3b valve may be provided it used would reduce the hazard by screening the detector I from the flammable vapors or gases outside the recess 3 which would be advantageous in case by some chance the detector 5 should reach a glowing temperature. However, by the automatic opening of the circuit to the detector 5, as above explained, there is protection against it becoming over-heated.

In case either of the resistors 5 or 5a or 13 or [5 in the two sides of the bridge circuit should become defective, as by open circuiting, the vane Ila would be moved to engage one or the other of the fixed contacts l'lb due to the unbalancing of the bridge circuit and thereby deenergize the magnet winding to give an alarm indication and disconnect the bridge circuit from the source until the defective resistor is replaced. In Fig. 2 the parts corresponding to those of are similarly designated may be any more or less closed space of any size, such as any compartment where hazardous vapors may form, for example, the hold or bilge of a ship, a room, or a building. At the right of the container 30 is shown a tank 3| containing under pressure an inert gas such as carbon dioxide. A pipe connects this tank with the upper portion of the container 30. A valve 32 in this pipe is automatically controlled by a magnet having a winding 33. One terminal of this winding is connected to the line 9 and the other terminal is connected to the fixed contact 19b through a switch 34 shown in the open position.

In placing the detecting and control apparatus in operative condition, the switch So will first be closed and then the push button switch 23, as already described with reference to Fig. i. This results in the contact ifla being moved to engage the fixed contact H! which closes the circuit of the safety light 26. The switch 34 will then be closed and have no effect on the control valve 32. However, if the condition of the gases and vapors within the container 30 is such as to be at or beyond a predetermined limit in the approach towards a dangerous condition, the contact galvanometer i? will act to deenergize the winding 20 and cause the contact i9a to engage the fixed contact iSb. In addition to the sig nals 21 and 25 being then energized, the winding 33 is excited to result in the automatic opening of the valve 32. This permits the passage of inert gas from the tank 31 to the container 30. When the gas and vapor mixture in the container has been reduced to a safe condition below the predetermined limit, as shown by the vane Ila disengaging the contact llb previously engaged by it, the operator may close the switch 23 momentarily for placing the apparatus in its normal protective condition. This, of course, permits the valve 32 to reclose and shut on the supply of inert gas until again required by the automatic control. The switch 34 in the circuit of the valve winding 33 will ordinarily be kept closed but may be opened by the operator for testing and for remedying any defects in other portions of the control apparatus without causing unnecessary opening of the inert gas control valve.

If desired a time delay control of the magnet for avoiding unnecessary opening of the inert gas valve. Fig. 3 shows a time delay relay which delays the opening of the gas valve upon the deenergization of the main operator to close the control winding. -.The relay is indicated as having a control winding 35 connected from the contact vIll) to the line 3 through a resistor 35a. The movement of its plunger is delayed in its upward movement by its piston being retarded in 5 the dashpot 36. The plunger actuates the movable contact 31 which is connected to the upper terminal of the valve winding 33. The fixed contact Ila is connected to line 9. It is obvious that the opening of the inert gas valve will always be n delayed a short interval of time after the contact l9a engages its fixed contact l9b, assuming the switch a to be closed. This will permit the push button switch 23 after the closing of the main switch 8a before the time delay control has closed the circuit of the valve winding 33 and thereby avoid unnecessary opening of the gas valve unless required by the condition of the gases and vapors in the container 30. Also it permits time for the operator to open the switch 34 if the deenergization of the main winding 20 is due to causes other than the condition of the gases and vapors in the container 30.

Although particular embodiments of this im: provement have been disclosed, it will be understood that various modifications may be made for adaptation to particular requirements without departing from the scope of the invention. The means responsive to the approach of a dan- '0 gerous condition and the device or devices automatically controlled .thereby may be of any desirable character to comply with the choice of the designer and the results to be obtained.

I claim:

1. Protective apparatus applicable to the presence of flammable vaporsand gases comprising a source of current, a circuit connected to said source containing a catalytic element, said element being located in the region to be tested for 40 the presence of such flammable vapors and gases and exposed thereto, a contact galvanometer electrically connected to said element and responsive to engage its contacts upon an increase in the resistance of said element and to its heating below its glowing temperature when said flammable vapors and gases increase to a predetermined amount and approach adangerous condition, anelectromagnet, contacts controlled by said electromagnet in the circuit of said element and closed when said electromagnet is energized, and connections between saidgalvanometer and the winding of said electromagnet for deenergizing said winding upon the contacts of said galvanometer making engagement and thereby opening .5 the circuit of said catalytic element, said galvanometer and electromagnet being located outside said region and at a distance therefrom.

2. Protective apparatus applicable to the presence of flammable vapors and gases comprising a source of current, a circuit connected to said source containing a catalytic element, said element being located in the region to be tested for the presence of such flammable vapors and gases and exposed thereto, a contact 'galvanometer electrically connected to said element and responsive to engage its contacts upon an increase in the resistance of said element and to its heating below its glowing temperature when said flammable vapors and gases increase to a predetermined amount and approach a dangerous condition, an electromagnet, contacts controlled by said electromagnet "in the circuit of said element and closed when said electromagnet is energized, con- 76 tance therefrom.

nections between said galvanometer and the winding of said electromagnet for deenergizing said winding upon the contacts of said galvanometer making engagement and thereby opening the circuit of said catalytic element, said galvanometer and electromagnet being located outside said region and at a distance therefrom, contacts engaged by the deenergization of said electromagnet, and a device actuated by engagement of said last named contacts for reducing th percentage presence of such vapors and gases.

3. Protective apparatus applicable to the presence of flammable vapors and gases comprising a source of current, a circuit connected to said source containing a catalytic element, said element being located in the region to be tested for the presence of such flammable vapors and gases andexposed thereto, a contact galvanom-' eter electrically connected to said element and responsive to engage its contacts upon an increase in the resistance of said element and to its heat.-.

ing below its glowing temperature when said flammable vapors and gases increase to a predetermined amount and approach a dangerous con-.

dition, an electromagnet, contacts controlled by said electromagnet irnthe circuit. of said element and closed when said electromagnet is energized,

connections between said galvanometer and the winding of said electromagnet for deenergizing said winding upon the contacts of said galvanometer making engagement and thereby opening the circuit of said catalytic element, said galvanometer and electromagnet being located outside said region and at a distance therefrom, a signal for v indicating danger upon the supply of current thereto, contacts engaged by the deenergization of said electromagnet, and circuit connections be:

tween said last named contacts and saidsignal for supplying current to said signal upon engagementof said last named contacts, said signal also being located outside said region and at a dis- WALTER J WILLENBORG.

REFERENCES cr'rn'n The following references are of record in the file of this patent:

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